This invention relates to an ultrasonic therapeutic apparatus, particularly a high intensity focused ultrasound (HIFU) scanning and treating system for tumor, which is an apparatus utilizing the sound intensity with high energy in the HIFU focal region to scan and treat the tumor tissues.
Ultrasonic wave is a mechanic energy with good directivity which can penetrate into the human body. People began to apply ultrasonic wave to the treatment and diagnosis of diseases long ago, then the ultrasonic physical therapeutic apparatuses such as A-ultrasonic apparatus, B-ultrasonic apparatus, etc. were made. The common feature of these apparatuses is that they produce very low sound intensity in the target tissue; usually the average intensity is below 3W/cm2. In the past 20 years, great achievements had been made in the field of ultrasonic diagnosis, and ultrasonic therapies were developed gradually and then very quickly; of which the progress in the development of ultrasonic thermotherapy and high intensity ultrasonic therapy is specially obvious.
Medical researchers have discovered that the heat-resistance of cancer cells is poorer than that of normal cells. When the temperature is between 42.5 and 45 degrees centigrade, the cancer cells die within 30 minutes while the normal cells are injured slightly and the injury is reversible. By utilizing this difference between cells and the thermal effect produced by ultrasonic wave, the ultrasonic thermotherapeutic apparatus was produced.
By retrieval, it has been found that the patent invention CN91105010.8,xe2x80x94xe2x80x9cUltra-high speed extrinsic ultrasonic high temperature therapeutic apparatusxe2x80x9dxe2x80x94belongs to the kind of apparatus mentioned above; the outstanding point of this patent invention is that treatments with sound intensity for a certain point (e.g. the center) of the target is carried out repeatedly; then the cells and tissues of the target (the tumor) are damaged by the diffusion of heat produced at the point. However, the effect of the apparatus is poor; the following are the reasons: 1. the active cancer cells are distributed mainly on the margin of the cancer mass; but the increase of temperature on the margin is relatively low; 2. The mass of cancer itself is irregular in shape, the shape of heat diffusion is difficult to control and there is temperature gradient; the non-invasive temperature measuring technique for tissues in deep parts of the body, especially the measurement of temperature increase and temperature gradient within the heat diffusion volume, is a worldwide difficult problem; 3. in order to put the irregular cancer mass under complete irradiation, it is unavoidable that the large amount of normal tissues are injured; 4. B-type echo detector is used within very short intervals between therapeutic wave beams to catch echo and to examine the A-type echo image of the degree of target damage during treatment; for this purpose, special image-storing circuit and sampling-comparing circuit are used; because only two successive A-type ultrasonic images are stored, it is difficult to observe the therapeutic effects directly; also it will make the apparatus complicated. 5. The therapeutic head can not aim at the target to carry out scanning movement, so the range of treatment is limited; it can not be used to treat the diffused point-like, branched, stripe-shaped, or other irregular shaped targets, or targets in relatively special locations.
Another patent application, CN93100813.1 shows xe2x80x9cA Method and an Apparatus which aims at the Target of Human Tissues to Carry out Treatmentxe2x80x9d. It puts stress on the description of a method aiming at the target of human tissues; in the method, a real-time acoustic distance-measuring recording probe and a therapeutic wave beam generator probe are used, and a visible reference mark is used to determine the theoretical location of one reference point in two wave beams; by means of the relative focus F in the coordinate system and the reference mark R the predetermined displacement is made, and by causing the visible reference marks of the acoustic distance-measuring record image to coincide and then displacing the mentioned therapeutic generator until the mentioned first and second reference marks coincide, one focus F of the therapeutic wave beam and the mentioned target are made to coincide. The apparatus can be used to give localized treatment for prostate only and its application to other parts of human body shows no significance.
A Europeans patent number EP0734742A2 shows the characteristics of an ultrasonic therapeutic equipment: By the action of first grade base frequency, the therapeutic ultrasound generator has the property of resonance oscillation. The driver drives the therapeutic ultrasound generator to work with the driving signal of the first grade base frequency. Using the driving signal of the second grade base frequency, the driver drives the ultrasonic probe to get ultrasonic image within the body, and receive the reflected wave of the first grade ultrasonic wave produced by the therapeutic ultrasound generator as well as the reflected wave of the second ultrasonic wave generated by the ultrasonic probe. The inventor has made effort to make a perfect combination of therapeutic ultrasound and image-displaying ultrasound, in the document, 14 modes are listed.
In recent years, in order to avoid the disadvantages of thermotherapy, people have made a lot of researches on the treatment of cancer with high intensity focused ultrasound (HIFU); in the so called HIFU therapy, the ultrasound emitted by the probe with relatively low average sound intensity (usually several W/M2) is focused or made to converge on a point of space, then a focal region with an average sound intensity over 1000W/M2 is formed; in the region instantaneous temperature elevation ( greater than 70 degrees centigrade) occurs, and cavitation or mechanical vibration occur, so the tissues in the focal region are damaged and the disease is cured.
A malignant tumor tissue has three marked characteristics: 1. because it is a tissue made up of juvenile cells, it is more sensitive to ultrasonic wave than the normal tissues. 2. it exists within the human body in three forms: a. in diffused point-like distribution, b. in the shape of a big mass, c. in the shape of tree-branches; 3. the malignancy degree of the tumor cells on the margin of the tumor is higher than that in the core of the tumor.
When the treatment of tumor tissue is carried out, injury of the normal tissue should be reduced as far as possible. The following are the difficulties in using HIFU technique to treat tumors: 1. a high energy point of ultrasonic wave (focal region) must be formed, and the ratio between the long axis and short axis of the focus region must be small; 2. the target tissue to be treated should be visible so that the location and shape of the tumor can be determined easily; 3. it should be possible to carry out scanning therapy for irregular tumors, and there should be various scanning forms for medical workers to choose. 4. it should be possible to perform real-time monitoring on the therapeutic effects. If B-mode ultrasound scanner is used for monitoring, strong ultrasonic reflection interfering B-ultrasonic image should be avoided, 5. the medium used should be a special liquid; the characteristic of its acoustic impedance should be similar to that of human tissues, and its acoustic attenuation should be little so that it will not interfere with the focused sound field.
According to the technical difficulties found in the treatment for tumors with HIFU, the purpose of developing this invention is to provide a high intensity focused ultrasonic system for scanning and treating tumors. By means of focusing, the system causes ultrasonic waves to form a space-point with high energy (focal region); the energy of the region reaches over 1000W/M2 and the temperature instantaneously rises to  greater than 70 degrees centigrade; besides, the focal region is made to enter the tumor tissue within the human body to carry out scanning movement, guaranteeing that its locus fully covers the tumor tissues to treat the tumor.
In order to realize the above purpose, the following design is adopted in the invention: the high intensity focused ultrasonic system for scanning and treating tumor comprises a combined probe, a high intensity power source, a B-mode ultrasound scanner, a multi-dimensional digit-controlled motional apparatus, a vacuum degassor, a therapeutic bed, and a computer operation system, of which, the combined probe comprises a therapeutic head which generates therapeutic ultrasonic waves and a image-displaying probe of B-mode ultrasound scanner; it is mounted on a motional apparatus which is made up of three-dimensional rectangular coordinate and one or two dimensional rotational coordinate. The upper end of the combined probe is connected to the central hole of the therapeutic bed through an open water bag; at the middle of the therapeutic bed there is a big hole for mounting the water bag (2); the lower end of the water bag (2) is connected to the head of the combined probe (3); the combined probe (3) is mounted on the motional system (4) with three-dimensional rectangular coordinate and two dimensional rotational coordinate; the combined probe (3) is also connected to the high frequency electric power source (6); the B-mode ultrasound probe is mounted on the central axis of the combined probe and connected to the B-mode ultrasound scanner: the motional system (4) is connected to the digit-controlled scanning system; the water bag (2) is connected to the vacuum degassor (5); the computer operation system (9) is separately connected to the high frequency electric power source (6), B-mode ultrasound scanner (7), digit-controlled scanning system (8), and the vacuum degassor.
The B-mode ultrasound probe is mounted on the central part of the therapeutic head; through adjustment, it is guaranteed that the space-point (focal region) produced by the therapeutic probe falls within the image-displaying plane of B-mode ultrasound scanner. The ultrasonic wave-emitting surface of the combined probe is located under the part to be treated and it is coupled to the skin by means of the open water bag; the medium used for this coupling is a kind of vacuum degassed water whose acoustic impedance is similar to that of human body and whose acoustic attenuation is little.
By means of the ball-screw, the stepping electric motor of the motional apparatus mentioned above drives the tract base to move on the ball tract. The real location of the movement is controlled by the location sensor which takes the location signal to realize the closed-loop control of the motional system; the multi-dimensional motional apparatus is formed by the combination and repeat addition of a certain number of single dimensional motional apparatuses.
The high frequency power source mentioned above comprises a signal source, a signal modulator, a magnifier, a matching box, a three-phase electric supply, a manual controller, an interface of computer, and a display device. The signal modulator is connected separately to the three-phase electric supply, signal source, interface of the computer, and the magnifier; the signal source is connected separately to the three-dimensional electric supply, magnifier, display device, manual controller; the magnifier is connected respectively to the three-phase electric supply and the matching box; the matching apparatus gives out 0.2-0.3 MHz high frequency continuous or pulse electric supply; the signal source gives out high frequency sine wave signal of low pressure small current, which is adjusted by the signal modulation electric circuit into continuous or 10-1000 Hz carrier wave signal. The vacuum degassor mentioned above is a vacuum degasification circulating water apparatus, which comprises a vacuum pump, a circulating water pump, a water box, a regulator of water temperature, a water bag of combined probe, and a controlling electric circuit. The water box is connected separately to the vacuum pump, regulator of water temperature, circulating water pump and the water bag of the combined probe; the controlling electric circuit is connected separately to the circulating water pump, regulator of water temperature, and the vacuum pump; the combined probe and water bag are connected separately to the circulating water pump. This apparatus conducts degasification on water, then the water is used as the medium for ultrasonic coupling.
Under the control of information-processing system, the multi-dimensional digit-controlled scanning system drives the stepping motor and puts the combined probe in motion to carry out two or three dimensional scanning movement, so that two or three dimensional scanning treatment or detect is performed on the target tissue within the body by the focal region (space-point) of the combined probe.
following are the advantages of the above therapy: 1. No surgery needed, little pain suffering; 2. the tumor scanned and ablated by HIFU remains within the body; medical researches show that when the treated tumor tissue is left in the body it can strengthen the immunity of the body; and can eventually be absorbed by the body and fibrosis occurs.
When the system mentioned-above is used, the tumor tissue is searched for by the sector scanning plane of the B-ultrasonic detector and the range to be treated is determined by the medical worker. The focal region of the therapeutic head is set at a location on the sector scanning plane of the B-mode ultrasound scanner through mounting, and the position is stored in computer memory. The computer, controlled by the medical worker, gives instructions to the digit-controlled scanning system and drives the therapeutic head to carry out the scanning movement; at the same time it gives instructions to the power source to turn on or off and adjust the strength of its power. Because the location of the focal region is in a fixed relation with the therapeutic head, and its movement parallels with that of local region, so the scanning movement of the therapeutic head outside the body guarantees that the focal region carries out scanning movement within the body.